A twin study of autism symptoms in Sweden
Résumé
This study aimed to empirically identify the number of factors underlying autism symptoms -- social impairments, communication impairments, and restricted repetitive behaviors and interests -- when assessed in a general population sample. It also investigated to what extent these different autism symptoms are caused by the same or different genetic and environmental influences. Autistic symptoms were assessed in a population-based twin cohort of >12,000 9- and 12-year-old children by parental interviews. Confirmatory and exploratory phenotypic factor analyses and multivariate structural equation model-fitting were carried out. A multiple factor solution was suggested, with nearly all analyses pointing to a 3-factor model for both males and females and at both ages. A common pathway twin model fit the data best, which showed that there were some underlying common genetic and environmental influences across the different autism dimensions, but also significant specific genetic effects on each symptom type. These results suggest that the autism triad consists of three partly independent dimensions when assessed in the general population, and that these different autism symptoms, to a considerable extent, have partly separate genetic influences. These findings may explain the large number of children who do not meet current criteria for autism but who show some autism symptoms. Molecular genetic research may benefit from taking a symptom-specific approach to finding genes associated with autism.
Origine : Fichiers produits par l'(les) auteur(s)
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